Successful treatment of a lung abscess without surgical intervention in a cat

CASE SUMMARY: An 8-year-old neutered female domestic shorthair cat was referred with complaints of lethargy, anorexia, fever, tachypnoea and a pulmonary mass on thoracic radiography. Whole-body CT revealed the presence of a nodular lesion in the right caudal lobe of the lung. Fine-needle aspiration of the lung mass yielded purulent fluid and cytology showed a large number of mildly to moderately degenerated neutrophils with numerous cocci and bacilli, leading to the diagnosis of a lung abscess. Empirical administration of doxycycline and orbifloxacin was initiated on the day of referral. Bacterial culture and antibiotic susceptibility tests using the collected fluid sample detected two types of bacteria, which were susceptible to both antibiotics. The clinical signs of the cat improved after the initiation of treatment, and the antibiotics were discontinued 28 days later, after the lung lesions disappeared. No recurrence of lung abscess was observed until 588 days after the discontinuation of treatment. RELEVANCE AND NOVEL INFORMATION: Only one case of a lung abscess has been previously reported in cats. Furthermore, while surgical resection is the most common treatment for lung abscesses in the field of veterinary medicine, this is the first report of successful treatment with antibiotic administration alone.